Recently, Dr. Joseph Mercola had yet another article about the danger and harmfulness of carbohydrates, and this time, he focused on the advice of another doctor, who mostly agrees with him that carbs are bad, but who also thinks that there are some "safe starches." For instance, rice and yams he regards as safe. But of course, that is only in small amounts, and like Dr. Mercola, he mostly wants people to eat animal foods and non-starchy vegetables. However, Dr. Mercola's purpose was to criticize that doctor and to question the whole idea that there are any "safe starches."
These doctors seem to think that anything that puts sugar into the blood is bad, and not just bad, but more like the worst thing one can possibly do. A doctor that Dr. Mercola favors most highly is Dr. Ron Rosedale who claims that there is no need for dietary carbohydrate at all, that the body can make all the glucose it needs from protein, and that's the best way to get it. He really thinks it's best not to consume any carbohydrate. It is the most extreme carbo-phobia I have ever come across.
But, I won't expound further about their ideas, not when I'm paying the freight. You can look them up online if you want to. I'm here to refute them and to point out the things that they are not saying. A lie by omission is just as big as an outright lie.
Of course, it is true that when you eat a food that is sweet or starchy that it adds sugar to the blood. But, your body doesn't just look the other way when that happens; it deals with it. Your body has a steady-state, an equilibrium for blood sugar, just as it has an equilibrium for potassium, sodium, and many other things. Piling sugar into the blood is definitely a disturbance of homeostasis, and your body responds to it. But, "disturbance" may be too strong a word because we are talking about a very normal, natural, everyday happening.
As soon as sugar starts entering your blood, your body starts sending it to the liver, where much of it is stored as glycogen. To give you an idea how much can be stored, the weight of the liver can rise by about 10% from a single meal due to glycogen storage. And if you are healthy and physically-fit, the process is very efficient. That stored glycogen becomes a steady source of glucose for the body between meals as your liver slowly releases it into the bloodstream to maintain a constant level of blood glucose. Think of it like a thermostat.
The muscles also store glycogen, but they are selfish about it. They store it only for their own use and not to share with the rest of the body. Glycogen is also stored in lesser amounts by the red blood cells, white blood cells, the kidneys, and certain brain cells called glial cells. So, this is a big deal. The body runs on sugar, and it stores it as glycogen so that meal-related fluctuations are minimized.     
How efficient is the process? It depends on how healthy you are. If your liver is healthy, it can store a lot of sugar and quickly. But, if it's diseased, say with fatty degeneration, then then the process is impaired. But that would not be the fault of carbohydrates. Or, if it's knarly and fibrotic from cirrhosis, glycogen synthesis and storage will also be impaired, but again, that would not be the fault of carbohydrates. And regarding the ability of muscles to make and store glycogen, it depends on how large the muscles are and how fit they are. The larger the muscle is, the more glycogen it stores. That is not to say that you need muscles as large as Arnold Schwartzenegger's. But, reasonably well-developed muscles are definitely a plus when it comes to sugar storage. And the more fit you are, the more accustomed you are to physical exertion, the more avidly your muscles store that glycogen. Therefore, if you have a healthy liver and strong, well-developed muscles, your tolerance for carbohydrates should be very substantial. You should be able to eat a lot of carbohydrate with only a modest and temporary rise in blood glucose.  
So, the question becomes: does a diet based on fat and protein, with practically no carbohydrates, result in healthier blood sugar levels than a diet high in unrefined carbs? It might seem like a no brainer that a low-carb or no-carb diet would be better in that respect, but don't be so sure. Dr. Mercola provided no clinical data about it, only fearmongering. And what about Dr. Kempner at the Rice House at Duke University? For decades, he put diabetics on a diet of rice and fruit to correct their diabetic condition, and he often got them off medication. How did that happen? Well, they dropped so much weight, and I mean fat-weight, that their insulin resistance went away, and so did their diabetes.   
So, besides having a healthy liver and fit muscles, the other thing that fosters tight blood sugar control is leanness. Having low body fat is necessary to keep insulin sensitivity sharp. When there is lots of body fat, then insulin resistance sets in, which means that glucose can't enter liver and muscle cells to be stored as glycogen. It's like the body is so overloaded with the fuel known as fat that it resists havng the fuel known as glycogen stored. So, there has to be leanness for the body to sanction the whole process. Diets high in unrefined carbs, meaning whole natural starches and intact whole fruits, support and encourage leanness. And that's why high-carb diets can actually help to improve blood sugar control.  
But, let's get back to the question of which diet actually works better in terms of glucose tolerance. First note that in order to make the comparison fairly, you would have to compare diets that were calorically equal. Obviously, if you had a low-carb meal that consisted of leafy green salad, cooked non-starchy vegetables, and a very small amount of meat or fish, it would likely raise the blood sugar a lot less than eating a whole pot-ful of beans and rice. The best approach would be to serve the same amount of salad and non-starchy vegetable to both parties, and then feed one the animal food and the other the equivalent in calories in, say, beans and rice. Who would win that contest? I think the plant fare would win, and I can tell you that attempts to remove carbohydrate from the diets of diabetics and just serve them protein and fat to control blood sugar have FAILED MISERABLY. Why? First, realize that just as the body can easily store glucose as glycogen, thereby removing it from the blood, the body can also very easily convert amino acids and the glycerol portion of fat into glucose, thereby adding sugar to the blood. So, if there are excess calories from protein and fat coming in, those excess calories can easily be converted into sugar. That process is known as gluconeogenesis.
And, you can't just look at the immediate effect on blood sugar; you have to look at the long term effects. It is widely known that high-protein/high fat/low carb diets do not support physical and athletic activity very well. The number of elite athletes who avoid carbohydrates, to the extent that Dr. Mercola and Dr. Rosedale recommend, is virtually zero. I just finished reading the biography of Lance Armstrong, winner of 7 Tour de France bicycle races, and I learned that before and during races, he loaded up on carbs: pasta, potatoes, rice, etc. Name me one top-tier elite endurance athlete who lives on salad and meat? You can't. There aren't any. That's because the body runs on carbs.
So, what I am getting at is that it's not just the food you are putting in- it's the activity you are putting out. And diets high in unrefined carbs support that output VERY WELL.
Keep in mind that I advocate including starches in the diet but not exclusively. I do not recommend eating nothing but starches and fruits and vegetables, as per McDougall or Esselstyn. Healthy fats are just as good for you as healthy starches, and I am for moderation with both. To demonize carbs or fats is extreme, and I mean really bizarre. The only thing more bizarre would be to demonize air or water. But, even though I consider Dr. Esselstyn's program extreme, it pays to look at him. I mean look at him physically. I have no doubt that he practices what he preaches. I'm sure he lives on nothing but starches, fruits, and vegetables. Well, the starches and the fruits are loaded with carbs, and even many of the vegetables he eats are, because I'm sure he eats potatoes, yams, corn, butternut squash, etc. And the result is: he is rail thin! Lean as a bone! But, what about what Dr. Mercola says about all the carbohydrate provoking all the insulin, and the high insulin levels making you fat, and that it happens even when the carbohydrates are unrefined? It isn't so. He made it up. 
So, what we are talking about is the paranoia of carbophobia, and the irony is that if Dr. Mercola were to get a woman pregnant, and if she were to give birth, and if he were to feed her his diet, her mammary glands would produce a high-sugar milk for that baby regardless- whether he liked it or not. Human breast milk is the sweetest milk on the planet- and by far. And even if he withheld carbs completely from her diet, her body would manufacture that lactose from scratch- if it had to- in order to provide the baby with what it needs and wants, which is: carbohydrates. Of course, for us adults, watching and controlling the total caloric intake is a very good idea. And when you restrict calories- to any extent- it will definitely reduce the strain on the whole system. But, the benefit comes from fewer calories, that is, less food. And, I am sure that most of us, including myself, could benefit from eating less food. But, let's concentrate on that and stop demonizing carbohydrates in particular. It's stupid. You know very well that you are not going to go the rest of your life without eating apples, bananas, yams, etc. So, why go down that road at all? It's just a form of extremism and paranoia. Find a good balance of protein, fats, and carbs in your diet; go for quality in all the foods that you eat; keep an eye on your total caloric intake, and cut out every single junk food; and also stay as physically active as possible. Also, try to avoid snacking. Eat your meals and "fast" in-between meals. That's the sensible, sane way to optimize your blood sugar.